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FZJ-2019-01042

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Messungen von Spurengasen und Photolyseraten während der FIELDVOC Kampagne in Pointe de Penmarc'h, Bretagne: Ein Beitrag zur Ozonbilanz

Harder, H.FZJ* ; Houben, N.FZJ* ; Pätz, H.-W.FZJ* ; Platt, U. ; Volz-Thomas, A.FZJ*

1995
Forschungszentrum Jülich GmbH Zentralbibliothek, Verlag Jülich

Please use a persistent id in citations: http://hdl.handle.net/2128/21494

Report No.: Juel-3144

Abstract: Measurements of O$_{3}$, NO, NO$_{2}$, NO$_{y}$, the photolysis frequency of NO$_{2}$, i.e. J$_{NO_2}$, and meteorological parameters were made with our mobile laboratory during a four week period in June 1993 at Pointe de Penmarc'h, which is located at the South-westem edge of the Bretagne. NO was measured with an improved version of the ECO Physics chemiluminescence instrument (Model CLD 770 Al ppt). For NO$_{2}$ a second chemiluminescence instrument was used in combination with a photolytic converter and NO$_{y}$, i.e. the sum of oxidised nitrogen compounds with an oxidation stage of II or higher, was converted to NO by conversion on a hot gold surface (T = 300K) in the presence of CO and measured with a third NO detector. The detection limits were 5, 20 and 50 ppt, respectively, for 1 h averages. Ozone was measured by UV absorption (Thermo Instruments, Model 49). The photolysis frequency of NO$_{2}$ was inferred from measurements ofthe (spherically integrated) actinie flux in the appropriate wavelength interval (320-420 nm) using a filter radiometer (MeteorologieConsult), which was calibrated by chemical actinometry. This report discusses the measurements and quality assurance procedures, as weIl as the comparison with data obtained by other techniques, e.g. differential optical absorption spectroscopy. The data are discussed in terms of distribution of emission sourees, prevailingmeteorology and chemical processing. The lowest NO$_{x}$ concentrations around or below 100 ppt were observed in maritime air during aperiod of strong westerlies. Much higher values were observed when the wind was from the land. In addition, the data were often influenced by nearby emission sources, such as fishing boats and automobile trafic. The measurements allowed the estimation ofthe photochemical ozone production rate P$_{O_3}$ and the concentration ofperoxy radicals from the photostationary state of NO and NO$_{2}$. These estimates are used to investigate the budget of O$_{3}$ in a land see breeze system. From the budget, it is suggested that substances other than peroxy radicals may have a strong influence on the NO$_{2}$/NO ratio at Penmarc'h and thus lead to an overestimation ofthe photochemical ozone formation rate. A likely candidate in these marine air masses is BrO, which is formed from the oxidation by O$_{3}$ of Br atoms that arise from the photolysis of methyl bromide. Thus, our data present some, albeit indirect, experimental support ofthe importance of halogen chemistry in the marine boundary layer.

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Contributing Institute(s):

1. Publikationen vor 2000 (PRE-2000)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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Database coverage:

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